1. Field of the Invention
The present invention relates to a signal processing device, a reproducing device, a signal processing method and a program. Particularly, the present invention relates to a signal processing device, a reproducing device, a signal processing method and a program that remove noise contained in a quantized signal.
2. Description of the Related Art
When a video signal that spatially varies very gently as shown in the upper middle of FIG. 19 is quantized, a generated digital video signal has a step-like waveform as shown in the middle left of FIG. 19, and a false contour is thereby generated. Specifically, a video signal, which is originally smooth, is changed into a step-like waveform, and a streak pattern like a contour line appears in the image. The streak pattern is called a false contour.
In view of this, the technique that eliminates the false contour by detecting a region where the false contour is generated and extending the bit length so as to smooth the signal as shown in the lower left of FIG. 19 has been proposed (cf. e.g. Japanese Unexamined Patent Application Publication No. 2007-221569).
Incidentally, digital signals of actual digital video contents in digital broadcasting or reproduced by DVD (Digital Versatile Disc), BD-ROM (Blu-ray Disc-ROM) or the like mostly have a waveform with an irregular step-like pattern as shown in the middle right of FIG. 19. This is because the step-like portion of the waveform is disturbed by noise S (which is also referred to hereinafter as false contour noise S) in the process of creating or compressing the contents.